on Electromagnetic Interference in Hospitals
By: Jeffrey M. Gilfor, M.D.
There has been a great deal of misinformation and hearsay associated
with reports about cell phones, LAN, and WAN in hospitals. Over
the past few months I have been accumulating reports, articles,
and data. Now seems the fitting time to report my findings.
First, a bit about jurisdiction:
The FCC has authority over all forms of equipment that is capable
to transmit electromagnetic (EM) energy. The FDA has authority over
all forms of medical equipment (both disposable and durable), medications,
and associated delivery systems or devices.
The FDA has never, and is prohibited from doing so by its charter,
banned any communications equipment. They have however, placed pre-market
requirements on medical equipment (i.e., shielding requirements).
The FCC has never banned transmitters (of any type) from hospitals;
providing that the equipment falls into FCC radiation flux level
There have been numerous discussions, meetings, publications, and
suggestions regarding the use of portable communications equipment
in the vicinity of medical equipment over the past 5 or so years.
Most of these dealt with problems reported in electric wheelchairs,
pacemakers, and anesthesia machines; which, due to inadequate shielding,
malfunctioned briefly while exposed to EM interference (EMI).
Apparently, as at least one source states it, a sign company propagated
the rumor of an FCC ban on cell phones in hospitals for the purpose
of selling its signs. It appears to have worked, and the ban on
cell phones in hospitals has grown to become one of the "urban myths"
of our society. Again, there is no such ban.
In England, then NHS (National Health Service) issued report DB9702,
"Electromagnetic Compatibility of Medical Devices with Mobile Communications."
In that 1997 report, only 4% of handheld transmitters (all types)
cause any interference at a distance of one meter (3 feet). Based
on that report, the agency recommended excluding those devices from
"sensitive" areas (OR, ICU, telemetry units). Also, the study stated
that, "The type of radio handset made a large difference to the
likelihood of interference. At a distance of 1m; 41% of medical
devices suffered interference from emergency services handsets,
35% suffered interference from security/porters handsets but only
4% from cellphones. No significant levels of interference were detected
from cordless handsets/local area networks or cellular base stations."
The report has not been updated.
Participants at the recent Health Canada medical devices roundtable
reached several conclusions. They agreed that a total ban of radio-frequency
transmitters in hospitals was not justified, and suggested suspectable
equipment should be removed if the source of EMI cannot be controlled.
They also recommended rational management of wireless telecommunication
devices used in hospitals. (Janice Hamilton, "Electromagnetic
interference can cause hospital devices to malfunction, McGill group
warns;" Canadian Medical Association Journal 1996; 154: 373-375)
Understanding that a ban on cell phones in hospital can not eliminate
the EMI constantly surrounding everything in an urban centers, and
fearing a backlash of public scrutiny about the issue; Cellular
Telecommunications Industry Association, in conjunction with the
FDA and FCC, and funded by a grant from Abbott, ran a series of
studies (conducted by the University of Oklahoma); to determine
what could be done about this problem. The studies concluded that
better pre-market testing and more stringent shielding requirements
are the answer to preventing EMI from causing medical equipment
malfunction. The latest data indicate that concern, especially with
newer PCA and spread-spectrum technologies, is overstated. Problems
occurred with low frequency (0.6%), only with a small portion of
devices used today, and only at very close distances (6") from the
The following are some references:
Newest PCS phones don't interfere with medical equipment (portion
As most TV sit-dram addicts know, things happen fast in hospital
emergency rooms. Since a few seconds can make the difference between
life and death, decisions must be made "on the fly," and clear,
fast communication is a must. But communicating with and keeping
track of staff and patients in an "ER" the size of Hennepin County
Medical Center's 53,000-square-foot facility is no simple matter.
With a number of "team centers" situated throughout the department,
"you can't just look down the hall and yell to somebody to help
you," said Jan Duroche, assistant nurse manager in the department.
Fortunately, HCMC greatly alleviated that concern last year when
it joined the growing ranks of Twin Cities hospitals installing
in-house cellular phone systems -- augmented by laptop computers
and PCs -- to improve staff communication and enhance patient
Published in the 6 September 1994 FDA Medical Bulletin.
Therefore, FDA recommends that clinicians and other device users
do the following:
Be aware that EMI can cause steady, momentary,
or intermittent disruption of the performance of medical devices.
Follow the recommendations of the device manufacturer
for avoiding EMI.
Purchase equipment that conforms to EMC standards.
Consider preventing known sources of interference
(e.g., cellular phones, hand-held transceivers) from coming
too close to patient monitors and other sensitive electronic
When an EMI problem is suspected, contact
the device manufacturer for assistance. Local clinical engineers
may also be able to assist in identifying and correcting the
Report device problems to FDA's MedWatch Program
and note if the problem is believed to be linked to interference
from a recognizable source of EM energy in the vicinity.
In perhaps the most complete report yet published by a US regulatory
agency, the FDA explains in, "Medical Devices and EMI: the
FDA Perspective," that it has worked, and will continue to
work with various other agencies and industry groups to ensure
that medical equipment is properly shielded against the constant
barrage of EM energy they are subject to. There is no mention
of a ban, or consideration for a ban, on EM sources (that comply
with FCC criteria) in hospitals. Deputy Director of Science and
Regulatory Policy for the US DHS, Phillip Phillips, reiterated
this view in his memorandum dated 6/13/95.
The following are additional FDA references regarding EMI and
medical equipment. Most date from 1994 and 1995:
Radiowaves May Interfere with Control of Powered Wheelchairs
and Motorized Scooters. Food and Drug Administration (September
20, 1994). 4 pages.
Update on Cellular Phone Interference with Cardiac Pacemakers.
Food and Drug Administration (November 1, 1995). 2 pages.
Williams, R.D. Keeping Medical Devices Safe from Electromagnetic
Interference. FDA Consumer, Vol. 29, No.4 (May 1995), pp. 12-16.
Witters, D.M. Medical Devices and EMI: The FDA Perspective.
ITEM Update (ISBN 1040-4716, 1995), pp. 22-32.